The invention relates to the field of medical suction canisters. In particular, the invention pertains to a filter and filter system for use in medical suction canisters.
Suction canisters collect body fluids in association with medical procedures and treatments are known. Typical suction canisters contain a reservoir and a lid attached thereto. The lid can be constructed to have a patient port, tandem port, vacuum port and exit port. In operation, a vacuum source and associated tubing are attached to the vacuum port of the lid, which is sealed onto the reservoir in an airtight manner. Upon activation, the vacuum source draws fluid and/or air from the patient into the reservoir, where the fluid is collected. As the canister fills with the fluid, the fluid level approaches the underside of the canister lid. Preventing the fluid from contaminating the vacuum source and its associated tubing is an important aspect of suction canister devices so as not to contaminate the secondary equipment and the user, as well as prevent obstruction or interference of the equipment.
A variety of automatic shut-off mechanisms for medical suction canisters have been developed. Most of these devices involve mechanical closure mechanisms, such as floating ball valves, and the like.
Filters which are positioned in the vacuum flow path, which activate upon contact with fluid, are also known. Such filters can be constructed of composite materials comprising porous plastic and fluid barrier materials, such as carboxymethylcellulose. When such composite materials come into contact with liquid, the materials respond by creating a barrier thereby preventing air and liquid flow through the filter. Certain materials, such as carboxymethylcellulose, increase viscosity by hydrating and xe2x80x9cgellingxe2x80x9d upon contact with water. Upon completion of such xe2x80x9cgellingxe2x80x9d, liquid and air flow are prevented from passing through the filter.
Several cylindrical hydrophobic filters having uniform interior diameters and uniform wall thickness are available. One example of such a filter is available from Domoch Medical Systems, Inc. (Riverside, Mo.), which has a cylindrical configuration having a constant outer diameter of about 1.05 inches (2.5 cm), a length of about 1.75 inches (4.45 cm), a uniform inner diameter of about 0.75 inches (1.9 cm), a uniform wall thickness of about 0.150 inches (0.4 cm), and a material volume of about 0.742 in3(1.9 cm3). Other hydrophobic cylindrical filters available from Abbott Laboratories, (Salt Lake City, Utah), DeRoyal Healthcare (Knoxville, Tenn.), and Allied Healthcare (St. Louis, Mo.) typically having a material volume of about 0.454 in3 (1.15 cm3). One disadvantage associated with currently available hydrophobic filters is their relatively large size and the amount of material used.
It would be advantageous to develop a hydrophobic, porous plastic filter for use in a suction canister which functions to automatically shut off air and fluid flow upon contact with a liquid. It would be even more advantageous to construct such a filter in a manner which is substantially effective but which has a smaller overall size and utilizes less material than currently available filters, thereby improves manufacturing efficiency.
The invention herein is a hydrophobic filter having a tapered hollow cylindrical configuration and adapted for use in medical suction canister systems. The filter of the invention comprises a variation in wall thickness along its length and is composed of a composite material comprising a porous plastic material and flow barrier material adapted to reduce and prevent air and liquid flow upon fluid contact therewith. The filter can be positioned in association with the lid of a suction canister system and between the vacuum source and reservoir of the canister.
The invention provides a hollow cylindrical filter for use in a suction canister comprising: a) first portion having an open end and a first wall thickness; b) a second portion having a closed end and a second wall thickness less than said first wall thickness; c) elongate central chamber having a substantially uniform diameter along its length; and wherein said filter is composed of a composite material comprising a porous plastic and a flow barrier material adapted to reduce and prevent air and liquid flow upon contact with a fluid.
The invention also provides a filter system for use in a suction canister having a lid and reservoir, the filter system comprising a hollow cylindrical filter and a filter shield. The filter shield functions both to reduce the likelihood of premature fluid contact on the filter from the lateral direction, and to attach the filter onto the underside of the suction canister lid. The filter shield for use with a suction canister having a lid and reservoir comprises: an outer portion and inner portion, each having a top and bottom portion, said inner portion having an inner sidewall and said outer portion having an outer sidewall; a shield chamber located within said inner portion and open at both ends; wherein the filter shield is adapted to attach to the underside of said suction canister lid; and wherein said shield chamber is adapted to receive and retain a hollow cylindrical filter within such that said inner sidewall laterally circumscribes said filter while exposing one end of the filter. In a preferred embodiment, the dimensions of the shield chamber accommodate the entire length of the filter when positioned within the filter shield. In an alternative embodiment, the filter shield can be integrally constructed as part of the lid.